No. I'm referring to diagnosis codes. For instance, abdominal pain. If a unspecified site is used, 789.00, vs. a specified site, 789.02, Do insurances ever deny a claim because the code is unspecified or pay at a lower reimbursement?

A claim generally is denied or paid. unless a modifier 52 (reduced service) is used. Do you have any examples of CPT with certian ICD-9 codes that are getting denied? I would check and find out what LCD the code is under and cross reference it on the cms website. Also in oregon OHP (oregon health plan) has the code sets available online so you can check to see if the code is payable with the diagnosis.